BR102017003243A2 - quaternary ammonium halides with functional ether groups for use as battery electrolytes - Google Patents

Abstract

It is an electrolyte solution and a flow cell battery. The electrolyte solution generally includes an electrolyte solution that includes one or more class A quaternary halides. The flow cell battery includes an electrolyte solution that includes one or more class A quaternary halides.

Description

(54) Title: QUATERNARY AMMONIUM HALETS WITH FUNCTIONAL Ether GROUPS FOR USE AS BATTERY ELECTROLYTES (51) Int. Cl .: H01M 4/60; H01M 8/18 (30) Unionist Priority: 1/20/2017 US 62 / 448,480 (73) Holder (s): ALBEMARLE CORPORATION (72) Inventor (s): ZHONGXIN GE; THANIKAVELU MANIMARAN; JOSEPH M. O'DAY (85) National Phase Start Date:

17/02/2017 (57) Abstract: It is an electrolyte solution and a flow cell battery. The electrolyte solution generally includes an electrolyte solution that includes one or more class A quaternary halides. The flow cell battery includes an electrolyte solution that includes one or more class A quaternary halides.

1/31 “QUATERNARY AMMONIUM HALETS WITH FUNCTIONAL ETHER GROUPS FOR USE AS BATTERY ELECTROLYTES”

FIELD OF TECHNIQUE [0001] In general, the present disclosure relates to electrolyte solutions and flow cell batteries that include an electrolyte solution.

BACKGROUND [0002] The reduction of diatomic bromine to two bromide ions has been used in electrolyte fluids in fluidizable batteries for decades. Battery types whose function depends on the bromine half reaction include zinc bromide, hydrogen bromide and vanadium bromide batteries. Such batteries usually contain a flowing electrolyte, which allows the electrolyte volume to increase, extending battery life before recharging is necessary. It also allows battery power to be recharged by replacing spent electrolyte fluids, while allowing common recharge methods to be used, if desired.

BRIEF SUMMARY [0003] However, even at relatively low concentrations, diatomic bromine has a propensity to form a vapor phase that separates from the liquid electrolyte, interfering with the charging of batteries containing bromine. For this reason, it is necessary to keep the concentration of free diatomic bromine in the electrolyte low enough, so that vapor phase formation does not occur. In addition, in addition to the tendency to vaporize free bromine, an abundance of free bromine in solution can lead to the direct oxidation of metal electrodes, such as the zinc electrode in the case of zinc bromide batteries. Thus, although bromine needs to be solvated in order to function as an electron donor / acceptor during battery use / recharge, the concentration is ideally maintained at only a low level.

[0004] In order to satisfy these requirements and still have a useful life

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2/31 of observable battery, the electrolyte solution of flow batteries containing bromine may contain an agent that performs complexation with elemental bromine, preventing the formation of a bromine vapor phase. The complex can form a separate layer from the rest of the electrolyte, essentially sequestering the complexed bromine away from the electrode in an oily phase. The degree to which the oil phase forms depends, to a certain extent, on the identity of the complexing agent. The complexing agent reliably retains diatomic bromine, which acts as a reservoir by releasing additional diatomic bromine into the electrolyte solution, since the one present in the solution is reduced to bromide ions. During battery cell recharging, as bromine is released, the complexing agent, which is soluble in the electrolyte, is regenerated and again becomes a component of the circulating electrolyte solution.

[0005] Complexing agents based on quaternary nitrogen halide generally have the ability to complex with at least one and, in some cases, four or more diatomic bromine molecules. In theory, the more diatomic bromine with which a complexing agent has the ability to complex, the longer the agent will have the ability to release bromine and the longer the life of the cell battery before recharging is required.

[0006] It has now been observed that increasing the length of the aliphatic chain of quaternary halide compound substituents improves the compound's ability to complex with diatomic bromine, providing complexes with increased amounts of bromine sequestered per quaternary compound molecule. However, in order to complex diatomic bromine, the molecule must also be soluble in an aqueous electrolyte solution; the complexing capacity of bromine is not persistent unless the complexing agent is solvated. In relation to quaternary halide compounds, attempts to increase the complexing capacity of bromine by increasing the length of

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3/31 aliphatic chain of nitrogen substituents has been satisfied / with the practical limitation of decreased solubilities. Thus, the molecules that have been used as complexing agents are, in general, relatively simple quaternary ammonium compounds that carry short aliphatic substituents, such as methyl and ethyl groups, in order to avoid impeding electrolyte solubility.

[0007] Flow battery cells can be placed in a wide variety of fundamental uses. Such uses reach a temperature range. The solubility of quaternary ammonium halide complexing agents (“quaternaries”) can be highly temperature dependent, with quaternary ammonium halide compounds used so far, such as dimethylethylpropyl ammonium bromide (DMEP) that has a cloud point of about 23.2 ° C (where “cloud point”, as used in this document, is that of a solution that is 0.7 M in DMEP and 2.5 M in ZnBr ₂ ). Many high-sequestering efficiency complexing agents have cloud points that are above about 20 ° C and therefore cannot be trusted to remain solvated in aqueous electrolyte solutions at temperatures below their respective cloud points, limiting , in addition to the uses to which the batteries can be placed. “High sequestration efficiency” is defined, for purposes of this document, to leave less than 1.5% by weight of free bromine from an initial mixture which is 0.7 M in complexing agent, 0.5 M in bromide of zinc, and 2 M bromine.

[0008] It has been found that the use of specific types of quaternaries containing ether, designated as “class A” quaternaries that are otherwise high solubility (characterized by a low cloud point) with other quaternaries can provide a mixture that has a solubility that is increased over the other quaternary itself, and most surprisingly, a free bromine characteristic that is surprisingly low compared to free bromine characteristics

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4/31 of the individual mixing components alone. “Cloud point” means the cloud point of an aqueous solution containing 0.7 M of complexing agent and 2.5 M of zinc bromide.

[0009] Thus, in one aspect, the present disclosure provides an electrolyte and a flow cell battery containing bromine that comprises the electrolyte. The electrolyte comprises one or more class A quaternaries that each have a molecular structure selected from the group consisting of:

[0010] where X 'is Br' or Cl ', or the quaternary is a mixture of both bromides and chlorides; Ri, _R2, R3, and _R5 are, independently, alkyl substituents having 12 or fewer carbon atoms; where R ^ R ₂ and R ₃ , can be hydrogen. R ₄ is an alkyl chain that has atoms

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5/31 carbon in the range of about 1 to about 10. R ₅ is the alkyl terminating group (to the right of the ether oxygen in all structures), R ₄ is the linking group (to the left of the oxygen of ether in all structures), R ₁ , and, if necessary, R ₂ and R ₃ , are the remaining groups attached to quaternary nitrogen. Other R groups, such as those ring substituents or those attached to non-quaternary nitrogen atoms, are classified as R ₆ , R ₇ , etc., and are independently hydrogen or alkyl substituents that have 12 or less carbon atoms , or, in other respects, from about 1 to about 7 carbon atoms, or from about 1 or 2 to about 4 carbon atoms.

[0011] Furthermore, it has been found that mixtures of class A quaternaries with specific quaternaries called “class B quaternaries” can have an acceptable cloud point and a surprisingly low free bromine. Thus, in an additional aspect, the electrolyte additionally comprises one or more tetraalkyl quaternaries of the following structure:

? ¹ Θ ix I ©

R ₂ -NR ₄ r ₃ [0012] or one or more of the following quaternary structures:

both bromides and chlorides; R ₁ , R ₂ , R ₃ , are independently hydrogen or alkyl substituents that have 12 or less carbon atoms; R4 is an alkyl chain that has carbon atoms in the range of about 1 to about 10. Other R groups, such as those ring substituents or those attached to non-quaternary nitrogen atoms, are

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6/31 classified as R ₆ , R7, etc., and are independently hydrogen or alkyl substituents that have 12 or less carbon atoms or, in other respects, from about 1 to about 7 carbon atoms, or from about 1 or 2 to about 4 carbon atoms.

[0014] In additional aspects, the one or more class B quaternaries have the following structure:

C- (CH ₂ ) nD [0015] where C and D are each independently selected from the group consisting of:

[0016] where X 'is Br- or Cl-, or the quaternary is a mixture of both bromides and chlorides, n is in the range of 1 to 100, R1, R ₂ , R3, are, independently, hydrogen substitutes or alkyl having about 12 or less carbon atoms, and R ₆ , R7 and R ₈ are, independently, hydrogen substituents or alkyl having 12 or less carbon atoms. In additional aspects, the one or more class B quaternaries is (or are) twinned butyl bonded dimethylethyl quaternary bromide which has the following structure:

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7/31

[0017] In one or more aspects, the electrolyte solution includes one or more class A quaternary halides containing ether, each of which has the molecular structure to leave

A-RCHjtE-CHCHjlFft-B [0018] where A and B are each independently selected from the group consisting of:

[0019] where E and F are each independently in the range

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8/31 from 1 to 10, n is in the range of 1 to 100, X 'is Br' or Cl ', or the quaternary is a mixture of both bromides and chlorides, Ri, R ₂ , R3, are, independently, substituents of hydrogen or alkyl that have about 12 or less carbon atoms, R ₄ is an alkyl chain that has carbon atoms in the range of about 1 to about 10, R ₅ is an alkyl group that has carbon atoms in range from about 1 to about 6, and, R ₆ , R7 and R ₈ are independently hydrogen or alkyl substituents that have 12 or less carbon atoms. In one or more aspects, R1, R ₂ and R ₃ are, independently, hydrogen or alkyl substituents that have carbon atoms in the range of about 1 and about 7. In additional aspects, R ₄ is an alkyl chain that has carbon atoms in the range of about 1 to about 4. In one or more respects, R ₅ is an alkyl group that has carbon atoms in the range of about 1 to about 4. In still additional aspects, the one or more class A quaternaries is (or are) twinned dimethylethyl quaternary bromide with diethylether bond which has the following structure:

ch ₃ ch ₃ [0020] Although the multiple modalities are revealed, still other modalities will become evident to those versed in the technique from the detailed description below. As will be evident, certain modalities, as revealed in this document, have the capacity to modify in several obvious aspects, all without departing from the spirit and scope of the claims as presented in this document. Consequently, the detailed description should be considered illustrative in nature and not restrictive.

DESCRIPTION OF THE MODALITIES [0021] Types of flow batteries in which the electrolytes of

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The present disclosure may be used include, but are not limited to, zinc bromide type flow cell batteries, vanadium bromide type flow cell batteries, Polysulfide bromine type flow cell batteries and hydrogen bromine flow cell batteries.

CLASS A QUATERNARY [0022] In one aspect, the present disclosure provides a zinc bromide electrolyte solution that comprises at least one "class A" quaternary containing ether. A class A quaternary has the following structure:

Laugh

I®

R₂-N —— R₄ O-R₅ ] χθ R₃ [0023] where X is Br or Cl^-, or the quaternary is a mixture of both bromides and chlorides; R₁, R₂ and R₃ they are, independently, hydrogen or alkyl substituents having 12 or less carbon atoms, or, more preferably, between about 1 and about 7 carbon atoms. R₄ is an alkyl chain that has carbon atoms in the range of 1 to 10 or, more preferably, that has carbon atoms in the range of about 1 to about 4. R₅ is an alkyl group that has carbon atoms in the range 1 to 10 or, more preferably, that has carbon atoms in the range of about 1 to about 4. In one aspect, R₁, R₂ and R₃ they are, independently, ethyl or methyl, and R4 is ethyl or methyl and R5 is methyl or ethyl. In one aspect, the sum of the lengths of R4, R5 and the interconnecting ether oxygen is in the range of about 3 to about 12 atoms, or in other respects, in the range of about 4 to about 6 atoms. In yet another aspect, the sum of the previous lengths is 4. In yet another aspect, X is Br .

[0024] In yet another aspect of the present disclosure, the electrolyte solution comprises two class A quaternary halides, a first quaternary and a second quaternary. In an additional aspect, both

Petition 870170010735, of 02/17/2017, p. 24/95

10/31 class A quaternary halides are quaternary ether halides, trialkyl, in which nitrogen bears three alkyl groups as well as an alkyl group between nitrogen and ether oxygen that comprises carbon atoms in the range of about 1 to about of 6, and in which the ether oxygen is also connected to another alkyl group that has 1, 2, 3, 4, 5 or 6 carbons. In additional aspects, the first class A quaternary halide is bromide (2-methoxyethyl) triethylammonium, a triethylether quaternary that has the following structure:

C2H5 IQ ^Br

I®

C ₂ H ₅ -NC ₂ H ₄ -o-CH ₃ c ₂ h ₅ [0025] and the second class A quaternary halide is diethylmethyl- (2-methoxyethyl) ammonium bromide, a diethylmethylether quaternary that has the structure a follow:

c ₂ h ₅ θ

I Br

I ©

H ₃ CNC ₂ H _4. -O-CH ₃ c ₂ h ₅ [0026] Other class A quaternary halides include quaternaries containing ether that have a molecular structure selected from the group consisting of the following structures:

I

II

III

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11/31

R ₄ Ο Rs V

r ₄ ο r ₅ VI [0027] where X 'is Br' or Cl ', or the quaternary is a mixture of both bromides and chlorides; R1, R ₂ , R3 are independently hydrogen or alkyl substituents that have 12 or less carbon atoms or, in other respects, from about 1 to about 7 carbon atoms, or from about 1 or 2 to about of 4 carbon atoms. R ₄ is an alkyl chain that has carbon atoms in the range of 1 to 10, or, in other respects, that has carbon atoms in the range of about 1 or about 2 to about 4. R ₅ is a group alkyl that has carbon atoms in the range of 1 to 6, or, in other respects, that has carbon atoms in the range of about 1 or 2 to about 4. In one aspect, R1, R ₂ and R ₃ are, independently, ethyl or methyl, and R ₄ is ethyl or methyl and R ₅ is methyl or ethyl. In one respect, the sum of the lengths of R ₄ , R ₅ and the interconnecting ether oxygen is in the range of about 3 to about 12 atoms or, in

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12/31 other aspects, in the range of about 4 to about 6 atoms. In yet another aspect, the sum of the previous lengths is 4. Other R groups, such as those ring substituents or those attached to non-quaternary nitrogen atoms, are classified R ₆ , R7, etc., and are, independently, substituents of hydrogen or alkyl having 12 or less carbon atoms or, in other respects, from about 1 to about 7 carbon atoms, or from about 1 or 2 to about 4 carbon atoms.

[0028] In additional embodiments, the present disclosure provides an electrolyte solution, for example, a zinc bromide electrolyte solution, which comprises one or more class A quaternaries containing ether, with each auaternary having the following structure:

A-KCHjfe-O-fCHjyts- ^B [0029] where A and B are each independently selected from the group consisting of:

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13/31 [0030] where X 'is Br- or Cl-, or the quaternary is a mixture of both bromides and chlorides, and where E and F are each 10 or less, or are each in the range of 1 to 10, or E and F are each in the range of 1 to 3, In some modalities, E can be 1,2, 3, 4, 5, 6, 7, 8, 9 or 10, and F can be 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10. In some embodiments, n is 100 or less, or is in the range of 1 to 100, or in the range of 1 to 10 In some embodiments, n can be 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10. Ri, R ₂ and R3 are independently hydrogen or alkyl substituents that have 12 or less carbon atoms. carbon or, more preferably, between about 1 and about 7 carbon atoms. R ₄ is an alkyl chain that has carbon atoms in the range of 1 to 10 or, more preferably, that has carbon atoms in the range of about 1 to about 4. R ₅ is an alkyl group that has carbon atoms in the range of 1 to 10 or, more preferably, which has carbon atoms in the range of about 1 to about 4. In some embodiments, R ^ R ₂ and R ₃ are, independently, ethyl or methyl, and R ₄ is ethyl or methyl and R ₅ is methyl or ethyl. In some embodiments, the sum of the lengths of R ₄ , R ₅ and the interconnecting ether oxygen is in the range of about 3 to about 12 atoms or, in other respects, in the range of about 4 to about 6 atoms . In yet another aspect, the sum of the previous lengths is 4. R ₆ , R7, and R ₈ are, independently, hydrogen or alkyl substituents that have 12 or less carbon atoms, or in other respects, from about 1 to about from 7 carbon atoms, or from about 1 or 2 to about 4 carbon atoms. In some embodiments, the one or more class A quaternaries is (or are) twinned dimethylethyl quaternary bromide with a diethylether bond that has the following structure:

ÇH ₃ ch ₃ ch ₃

CLASS B QUATERNARY

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14/31 [0031] In additional aspects, the present disclosure provides a zinc bromide electrolyte solution comprising one or more class A quaternary halides and one or more "class B" quaternary halides. Class B quaternary halides can be of a variety of types. In one aspect, the class B quaternary halide may be one or more tetraalkyl quaternarys comprising four alkyl substituents R ₁ , R ₂ , R ₃ and R ₄ , wherein the substituents are independently alkyl groups within the range of about from 1 to about 10 carbon atoms and, in other respects, in the range of about 1 to about 6, or about 1 to about 4 carbon atoms. In one respect, class B quaternary halide is triethylpropylammonium bromide:

Í ^2HS ΒΓθ

I © c ₂ h ₅ -n — c ₃ h ₇ c ₂ h ₅ [0032] In another aspect, the class B quaternary is an alkylpiperidinyl quaternary halide, in which the piperidine ring can be substituted alkyl, and nitrogen quaternary may carry, in addition to the piperidinyl bonds, one or two alkyl groups. In one aspect, the piperidinyl ring is unsubstituted.

[0033] In some ways, the alkyl groups, R ₁ , R ₂ , are independently hydrogen or alkyl substituents having 12 or less carbon atoms or, more preferably, between about 1 and about 7 carbon atoms . In a particular aspect of the invention, R ₁ , and R2 are, independently, ethyl, methyl or propyl. In another particular aspect, the piperidinyl ring is unsubstituted and R1 and R2 are ethyl groups and X ^- is Br ^- .

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15/31

[0034] In another aspect, one of the alkyl groups is a propyl group.

[0035] In additional aspects, the class B quaternary halide comprises one or more quaternary compounds that have a molecular structure selected from the group consisting of the following structures:

I

II

III

IV

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16/31

LOL

R ₂

VI [0036] where X 'is Br' or Cl ', or the quaternary is a mixture of both bromides and chlorides; R ^ R ₂ , R ₃ are independently hydrogen or alkyl substituents that have 12 or less carbon atoms or, in other respects, from about 1 to about 7 carbon atoms, or from about 1 or 2 to about 4 carbon atoms. R ₄ is an alkyl chain that has carbon atoms in the range of 1 to 10, or, in other respects, that has carbon atoms in the range of 1 or 2 to 4. In additional aspects, R ^ R ₂ , R ₃ and R ₄ are, independently, ethyl or methyl. Other R groups, such as those ring substituents or those attached to non-quaternary nitrogen atoms, are classified R ₆ , R7, etc., and are independently hydrogen or alkyl substituents that have 12 or less carbon atoms or, in other respects, from about 1 to about 7 carbon atoms, or from about 1 or 2 to about 4 carbon atoms.

[0037] In additional modalities, the class B quaternary halide comprises one or more quaternary compounds that have the following structure:

C- (CH ₂ ) nD

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17/31 [0038] where C and D are each independently selected from the group consisting of:

[0039] where X 'is Br- or Cl-, or the quaternary is a mixture of both bromides and chlorides, and where n is 100 or less, or is in the range of 1 to 100, or in the range of 1 to 10. In some embodiments, n can be 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10. Ri, R ₂ and R ₃ are independently hydrogen or alkyl substituents that have 12 or less carbon atoms or, more preferably, between about 1 and about 7 carbon atoms. R ₄ is an alkyl chain that has carbon atoms in the range of 1 to 10 or, more preferably, that has carbon atoms in the range of about 1 to about 4. R ₅ is an alkyl group that has carbon atoms in the range of 1 to 10 or, more preferably, having carbon atoms in the range of about 1 to about 4. In some embodiments, Ri, R ₂ and R ₃ are, independently, ethyl or methyl. R ₆ , R7, and R ₈ are independently hydrogen or alkyl substituents that have 12 or less carbon atoms or, in other respects, from about 1 to about 7 carbon atoms, or from about 1 or 2 to about 4 carbon atoms. In some

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18/31 modalities, the one or more class B quaternaries is (or are) twinned butyl bonded dimethylethyl bromide which has the following structure:

[0040] The electrolytes described in this present disclosure, both those comprising class A quaternary halide, and those comprising a mixture of class A and class B quaternary halides are suitable for membraneless and membrane-containing aspects. In other respects, the present disclosure provides flow cell batteries containing bromine that contains the electrolyte solution.

[0041] In some embodiments, the present disclosure provides a flow cell battery, such as a zinc bromide flow cell battery, which comprises an electrolyte solution comprising one or more class A quaternary halides, or a mixture of one or more class A quaternary halides and one or more class B quaternary halides.

ELECTROLYTE SOLUTION [0042] In one aspect, the complexing agent is a class A quaternary halide and is present in the electrolyte solution in a concentration in the range of about 0.1 to about 3.0 moles per liter and, in other respects, in the range of about 0.2 to about 2.0 moles per liter, and in still other aspects, in the range of about 0.5 to about 1.0 moles per liter, based on volume total electrolyte solution.

[0043] In another aspect, the electrolyte solution comprises both at least one class A quaternary halide and at least one class B quaternary halide; where the molar ratio between class A and class B quaternary halide is in the range of about 0.02 to about 50, in

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19/31 a more restricted aspect, in the range of about 0.2 to about 5 and, in an even more restricted aspect, about 1: 1. The total molarity (or% by weight, where appropriate) of class A and class B quaternaries is in the range of about 0.1 M to about 3.0 M and, in a more restricted aspect, in the range of about from 0.5 M to about 1.0 M.

[0044] The electrolyte solutions of the present disclosure can be used with a wide range of zinc bromide concentrations, including those in common use in the art. In one aspect of the present solution, the zinc bromide solution has a zinc bromide concentration in the range of about 0.1 to about 3 M. In a more restricted aspect, the zinc bromide concentration is in the range of about 1.5 to about 2.5 M.

[0045] The electrolyte solution can be used in a wide variety of flow cell batteries, such as membrane-containing and membrane-free designs known in the art. The necessary battery components include a flow cell with bipolar electrodes and auxiliary equipment such as pumps, electrolyte reservoir and bromine complex storage. Other battery components that can be used with batteries containing the electrolyte solution include Bromine, Zinc Chloride, Ammonium Chloride and Potassium Chloride.

[0046] In general, the electrolyte solutions of the present disclosure have a plating efficiency in the range of about 50% to about 100% and, in other respects, in the range of 75% to about 100%.

[0047] The previous plating efficiency parameters are as follows:

[0048] Test conditions: 25 ° C; 2-electrode cell configuration;

[0049] Working Electrode:

[0050] Conductive graphite rod (d = 0.635cm or 1/4 inch, length 5 cm, surface area ~ 10cm ² )

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20/31 [0051] Counter / Reference Electrode:

[0052] Conductive graphite rod (d = 0.635 cm or 1/4 inch) [0053] Equipment: MTI battery tester [0054] Electrolyte: 35 ml 2.5 m ZnBr ₂ , 0.05 M Br ₂ and 0 , 7 M Polibromide complex [0055] 30 mA for 5 hours (total ~ 150mAh plating capacity) unstirred condition [0056] The working electrodes were thoroughly cleaned by washing DI water and dried after zinc plating. Plated zinc on working electrode was determined by measuring the difference in working electrode weight before and after plating test. The zinc plating efficiencies were calculated by real zinc weight over theoretical zinc weight, which was obtained by the Faraday law of electrolysis assuming 100% 180 mAh capacity conversion.

[0057] The class A quaternary electrolyte solutions of the present disclosure generally have cloud spots (as defined in this document) at temperatures of less than about 25 ° C, in some respects, less than about 0 ° C and, in still other aspects, less than about -10 ° C. The electrolyte solutions of the present disclosure that comprise both class A and class B quaternaries generally have cloud points of less than about 25 ° C, with some mixtures exhibiting cloud points of less than 5 ° C.

[0058] The operation in front of a battery containing bromine generally involves the conversion of elemental bromine into ionic bromine. The quaternary / Br ₂ complex results from an equilibrium reaction in which Br ₂ is released from the complex as the concentration of free Br ₂ in the aqueous electrolyte drops during battery operation. In its fully charged state, the electrolyte solution inevitably contains some degree of uncomplexed bromine. A measure of a quaternary ability to complex elemental bromine is the amount of elemental bromine left in

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21/31 solution when the complexation reaction proceeds to equilibrium. Such bromine is called "free bromine". The measurement of free bromine in the aqueous phase is set out in Example 1.

[0059] The amount of free bromine depends on the characteristics of the complexing agent, such capacity to remain bromine, as well as the ease with which bromine disassociates from the complexing agent. In aspects where the class A quaternary is used without the use of a class B quaternary, it is preferred that the free bromine of the quaternary, as measured by the procedure of Example 1, is less than about 1.5% by weight and, in more restricted aspects, less than about 0.7% by weight. If a class A / class B quaternary mixture is being used, it is preferred that the free bromine in the mixture is less than about 1.0% by weight and, in less restricted aspects, less than about 0.5 % by weight.

[0060] The bromine-containing cells of the present disclosure can, in general, be operated over a wide temperature range. Although other complexing agents in the art become crystalline at low temperatures, the cells of the present disclosure can, in general, be operated at temperatures as low as 0 ° C and, in other respects, as low as -10 ° C.

[0061] In general, the quaternary ammonium bromide compounds disclosed in this document can be used in electrolyte solutions that include diatomic bromine as a component. Such flow batteries include, for example, zinc bromide, hydrogen bromide and vanadium bromide batteries. One aspect of the present disclosure is a zinc bromide battery comprising an electrolyte solution containing one or more class A quaternary halides, or a mixture of one or more class A quaternary halides with one or more class B quaternary halides. In additional aspects, the zinc bromide battery contains an electrolyte solution that comprises one or more

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22/31 plus Ada class quaternary halides structure as follows:

? ¹

I®

R ₂ -N —— R ₄ OR ₅

I χΘ R ₃ [0062] and, optionally, one or more class B quaternary halides of the following types:

Laughs, ©

-N — R _d [0063] and ^R X © / ² Θ .n. x

[0064] where the R substituents are as provided herein for the corresponding structures. In more restricted aspects, the zinc bromide battery comprises an electrolyte solution that comprises two class A quaternary halides of the following structures:

θ

Br

I ©

C ₂ H ₅ -N- C ₂ H4-OC H ₃ c ₂ h ₅ [0065] and ç ₂ h ₅ q Br

I®

H ₃ CNC ₂ H ₄ -O-CH ₃ c ₂ h ₅ [0066] In another more restricted aspect, the zinc electrolyte battery comprises an Ada class quaternary halide with the following structure:

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23/31

0> Η ₅ ÇjHg Q Br ©

\ l — c ₂ h ₄ - o — ch ₃

C2H.

[0067] and class B quaternary halide from one of the following structures:

I® ^Br

C ₂ H _c -NC ₃ H ₇

C2H5 [0068] or

Ο

Br [0069] or

C ₂ H _5/3 ^Η 7

Θ

Br

[0070] Complexing agents can be used in aspects without a membrane. In one aspect, the present disclosure discloses a membrane-free flow cell battery comprising an electrolyte solution comprising one or more class A quaternary halides, or a mixture of one or more class A quaternary halides and one or more halides class B quaternaries

EXAMPLES EXAMPLE 1 [0071] Measurement of free bromine in aqueous phase:

[0072] Two slightly different methods were used to prepare the electrolyte compositions, A) one containing 0.7 M quaternary

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24/31 and B) the other containing 0.8M of quaternary. In composition A, 2.0 moles of bromine was added to an aqueous solution containing 0.5 moles of zinc bromide and 0.7 moles of quaternary. The two-phase mixture was stirred for 24 h and then the phases were allowed to settle. The top aqueous phase was sampled for measurement of free bromine. In composition B, 1.44 moles of bromine were added to an aqueous solution containing 0.5 moles of zinc bromide, 0.4 moles of zinc chloride and 0.8 moles of quaternary. The top aqueous phase obtained after stirring for 24 h was used to measure free bromine.

[0073] A 250 ml flask of Erlenmeyer was loaded with 50 ml of deionized water and weighed (A). A sample of the clean aqueous phase was passed through glass wool to remove any suspended organic phase and then added to the Erlenmeyer flask. The flask was weighed again (B) and the difference in weight (B-A) was observed as the weight of the sample. About 20 ml of 20% potassium iodide solution followed by about 5 ml of starch solution was added to the flask. The resulting dark mixture was titrated against 0.02N sodium thiosulfate solution. The final point was the disappearance of purple color. Free bromine (% by weight) was calculated as follows:

[0074]% by weight of free Br ₂ = Volume (ml) of sodium thiosulfate x Normality of sodium thisosulfate / Sample weight.

EXAMPLE 2 [0075] Cloud point determination:

[0076] 1 A 0.7M quaternary ammonium bromide in 2.5M aqueous zinc bromide solution was prepared.

[0077] 2. The solution was transferred to a jacketed flask with a stir bar and temperature monitoring.

[0078] 3. The solution was heated to 15 ° C above the expected cloud point. If necessary, any moisture or impurities were removed by filtration.

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25/31 [0079] 4. The solution was stirred, with speed adjustment at about 250 rpm, while preventing the formation of bubbles.

[0080] 5. The solution was cooled gradually (cooling rate about 1 ° C / 5min).

[0081] 6. The sample was inspected carefully for signs of cloudiness, and the temperature at which cloudiness was observed was recorded closer to 0.1 ° C.

[0082] It is noted that step 3 may require the performance of an approximate cloud point measurement to roughly determine an expected cloud point. Such measurement can be carried out by preparing a solution according to steps 1 and 2, and subjecting it to a temperature drop from an initial temperature that is greater than any expected cloud point, such as, for example, about 45 ⁰ C.

[0083] Examples 3 to 7 and 9: The cloud and free bromine points were measured according to Examples 1 and 2, respectively

EXAMPLE 3

Name Structure MW ZnBr ₂ Cloud Point Solubility Br2 free 2 Triethylether Quaternary Bromide C2 ^H 5 Q Br 1 © C ₂ H ₅ -NC ₂ H ₄ -O-CH ₃ C2H ₅ 240 0.7M, <-10.5 Ç p 0 00 5 Bromide quaternary in triethylpropyl ^C 2 ^H 5 Q Br 1 © C2H5-N- ^C 3H7 C2H5 224 0.7M, 41.2C 0.7M 0.089 % 6 Mix 50/50 mol% of 1 and 4 232 0.7M, 10.5 C 0.7M 0.25%

[0084] The free bromine of compound 2 at 0.7M is 0.658%, and that of compound 5 is 0.089%. However, the 50/50 mol% ratio of the two compounds

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26/31 has a free bromine of 0.25% to 0.7M, which is a significant drop in free bromine of more than 50% compared to the free bromine of the triethylether quaternary alone.

EXAMPLE 4

Name Structure MW ZnBr ₂ cloud point solubility Br2 free 1 Dimethylbutileter Quaternary Bromide CH3 C4H9-N + C2H4 — OCH3 1 ^Br 'CH3 240 0.7M, 29 C 0.7M 0.28% 4 Quaternary Bromide from Diethylmethyleter C2 ^H 5 © Br 1 © H ₃ C NC ₂ H ₄ -OC C2H ₅ 226 0.7M, <-10.5 C 0.7M 0.70% 7 Mix 50/50 mol% of 1 and 2 233 0.7M, 9C 0.7M 0.22%

[0085] It is observed that compound 4 differs from compound 1 only in having 1 less carbon atom in one of its methyl groups. The free bromine at 0.7 M can be expected to be greater than that of compound 1.

[0086] However, the 50/50 mol% ratio of the two compounds has a free bromine of 0.22% at 0.7 M, which is similar to that of compound 1.

EXAMPLE 5

Name Structure MW ZnBr2 cloud point solubility Free br2 2 Triethylether Quaternary Bromide C2H5 © Br 1 © C ₂ H ₅ -NC ₂ H ₄ -O-1 C ₂ H ₅ ^C 240 0.7M, <-10.5 C 0.8M 0.467% 9 Diethyl Piperidine Bromide C2H5 ~ / ^C 2 ^H 5 \ © / © .xN. Br 222 0.7M, 11.9 C 0.8 M 0.26%

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27/31

12 Mix 50/50 mol% of 1 and 6 231 0.7 M, -3 C 0.8 M 0.27%

[0087] The free bromine of compound 2 at 0.8 M is 0.477%, and that of compound 9 at 0.8 M is 0.26%. A 50/50 mol% ratio of the two compounds has a surprisingly low free bromine of 0.27% at 0.8 M.

EXAMPLE 6

Name Structure MW ZnBr ₂ cloud point solubility Free br2 2 Triethylether Quaternary Bromide C2 ^H 5 © Br 1 © C ₂ H ₅ -NC ₂ H ₄ -O— C ₂ H ₅ 240 0.7M, <-10.5 C 0.8 M 0.477% 10 EtiPropila Piperidine Bromide C2H5 ~ / ^C 3 ^H 7 / N. Br 236 0.7M, 45.8 C 0.8 M 0.026% 13 Mix 50/50 mol% of 1 and 8 238 0.7M, 18.8 C 0.8 M 0.062%

[0088] The free bromine of compound 2 at 0.8 M is 0.467%, and that of compound 10 at 0.8 M is 0.026%. A 50/50 mol% ratio of the two compounds has a surprisingly low free bromine of 0.062% at 0.8 M.

EXAMPLE 7 [0089] Test Conditions: 25 ° C [0090] 2-electrode cell configuration [0091] Working electrode:

[0092] Conductive graphite rod (d = 0.635 cm or 1/4 inch), length 5 cm, surface area ~ 10cm ² ) Counter / Reference Electrode:

[0093] Conductive graphite rod (d = 0.635 cm or 1/4 inch) [0094] Equipment: MTI battery tester

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28/31 [0095] Electrolyte: 35 ml 2.5m ZnBr2, 0.05M Br ₂ and 0.7 M Polybromide complex [0096] 30 mA for 5 hours (total ~ 150mAh plating capacity) unstirred condition [0097] The working electrodes were carefully cleaned by washing Dl water and dried after zinc plating. Plated zinc on working electrode was determined by measuring the difference in working electrode weight before and after plating test. The zinc plating efficiencies were calculated by real zinc weight over theoretical zinc weight, which was obtained by the Faraday law of electrolysis assuming 100% 180 mAh capacity conversion.

Complexing Agent Plating Efficiency MEP 59.88% Example-3 Merges 79.05% Example-4 Merges - Example-5 Merges 74.65% Example-6 Merges 98.38%

EXAMPLE 8

Chlorine Quaternary Bromine Quaternary [0098] Chloride ions are added to the electrolyte in sufficient quantities to reduce the amount of free bromine present and increase the electrolyte conductivity during cell loading. The chloride ions in the electrolyte can originate from a quaternary ammonium chloride or zinc chloride complexing agent.

[0099] Experiment 1 of Example 8: An aqueous electrolyte system was prepared having 0.84 M of zinc bromide, 0.8 M of quaternary

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29/31 chlorine (N-methyl chloride, N-butyl pyrrolidine) and 1.44 M bromine. After the sample was stirred for 24 h at 35 ° C, the amount of free bromine present in the electrolyte was 0.26%.

[00100] Experiment 2 of Example 8: An aqueous electrolyte system was prepared having 0.84 M of zinc bromide, 0.8 M of bromine quaternary (N-methyl bromide, N-butyl pyrrolidine) and 1.44 Bromine M. After the sample was stirred for 24 h at 35 ° C, the amount of free bromine present in the electrolyte was 0.25%.

Component Experiment 1 Experiment 2 Concentration (M) Concentration (M) ZnBr ₂ 0.84 0.44 ZnCI ₂ 0 0.40 Br ₂ 1.44 1.44 Bromo Quaternary 0 0.8 Chlorine Quaternary 0.8 0

EXAMPLE 9

Name Structure MW Solubility and Point Cloud ZnBr ₂ Br ₂ free 14 Quaternary Dimethylethyl Bromide Twinning with Bonding Dietileter çh ₃ ch ₃ 378 0.7 M, 48.2 C 0.7 M 0.71% 15 Quaternary Dimethylethyl Bromide Twinned with butyl bond ch ₃ I C ₂ H ₅ - ^Ν \ ^ΒΓ θχ- \ ch ₃ 362 0.7 M, 89.2C 0.7 M 0.59%

[00101] The free bromine of compound 14 at 0.7 M is 0.71%, and that of compound 15 at 0.7 M is 0.59_%.

[00102] The components referred to by the chemical name or formula anywhere in the specification or claims therein, if referred to in the singular or plural, are identified as existing before

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30/31 to come into contact with another substance referred to by the chemical name or chemical type (for example, another component, a solvent, or etc.). No matter what changes, transformations and / or chemical reactions, if any, occur in the resulting mixture or solution as changes, transformations and / or reactions are the natural result of putting the specified components together under the conditions required in accordance with this revelation. In this way, the components are identified as ingredients to be brought together in connection with the performance of a desired operation or in the formation of a desired composition. In addition, while the claims may now refer to substances, components and / or ingredients in the present ("comprise", "is", etc.), the reference is to the substance, component or ingredient as it existed in the moment immediately before it was first contacted, mixed or mixed with one or more other substances, components and / or ingredients in accordance with the present disclosure. The fact that a substance, component or ingredient may have lost its original identity through a chemical reaction or transformation during the course of contact, mixing or mixing operations, if conducted in accordance with this disclosure and with the common skill of a chemist, it is not, therefore, of practical concern.

[00103] The invention may comprise, consist or consist essentially of the materials and / or procedures cited in this document.

[00104] As used in this document, the term "about" which modifies the amount of an ingredient in the compositions of the invention or used in the methods of the invention refers to the variation in the numerical amount that can occur, for example, through typical liquid handling and measurement used to produce concentrates or use real-world solutions; through inadvertent error in these procedures; through differences in manufacturing, source,

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31/31 or purity of the ingredients used to produce the compositions or perform the methods; and the like. The term about also encompasses amounts that differ due to different equilibrium conditions for a composition that results from a particular initial blend. Whether or not modified by the term "about", the claims include equivalent amounts.

[00105] Except as may be expressly stated otherwise, the article "one" or "one" if and as used herein, is not intended to limit, and should not be construed as limiting, the description or a claim to a single element to which the article refers. Instead, the article “one” or “one” if and as used in this document, is intended to cover one or more such elements, unless the text expressly states otherwise.

[00106] Each and every patent or other publication or published document referred to in any portion of this specification is incorporated in toto in this disclosure by reference, as set out in this document completely.

[00107] This invention is susceptible to considerable variation in its practice. Therefore, the foregoing description is not intended to limit, and should not be construed as limiting, the invention to the particular exemplifications presented above in this document.

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1/11

Claims (26)

1. Zinc bromide electrolyte solution CHARACTERIZED by the fact that it comprises one or more class A quaternary halides, each class A quaternary halide having a molecular structure selected from the group consisting of: Laugh Ra-Rj.-0-% I Χθ Ra I [[where X 'is Br' or Cl ', or the quaternary is a mixture of both bromides and chlorides; Ri, R ₂ , R 3, are independently hydrogen or alkyl substituents that have about 12 or less carbon atoms; R ₄ is an alkyl chain that has carbon atoms in the range of about 1 to about 10; R ₅ is an alkyl group that has carbon atoms in the range of Petition 870170010735, of 02/17/2017, p. 47/95 2/11 about 1 to about 6; and R ₆ , R7 and R ₈ are, independently, hydrogen or alkyl substituents that have 12 or less carbon atoms. 2. Electrolyte solution, according to claim 1, CHARACTERIZED by the fact that the one or more class A quaternary halides comprise at least one quaternary of structure I. 3. Electrolyte solution, according to claim 2, CHARACTERIZED by the fact that X 'is Br' or Cl 'or a mixture thereof; R1, R ₂ and R ₃ comprise about 1 to about 4 carbon atoms; and R ₄ comprises about 1 to about 4 carbon atoms; and R ₅ comprises about 1 to about 4 carbon atoms. 4. Electrolyte solution, according to claim 3, CHARACTERIZED by the fact that it comprises a first class A quaternary halide and a second class A quaternary halide: where in the first class A quaternary halide, R1, R ₂ and R ₃ are ethyl, R ₄ is ethyl and R ₅ is methyl; and in the second class A quaternary halide, R1 and R ₃ are ethyl, R ₂ is methyl, R ₄ is ethyl and R ₅ is methyl. 5. Electrolyte solution according to claim 1, CHARACTERIZED by the fact that the electrolyte additionally comprises one or more tetraalkyl quaternary halides of the following structure: r ₂ -n— R3 where Petition 870170010735, of 02/17/2017, p. 48/95 3/11 X- is Br- or Cl- or a mixture thereof, and the substituents Ri, _R2, R3 and _R4 are independently alkyl groups included in the range of about 1 to about 10 carbon atoms. 6. Electrolyte solution according to claim 5, CHARACTERIZED by the fact that R1, R ₂ , R3 and R ₄ are, independently, alkyl groups comprised in the range of about 1 to about 4 carbon atoms. 7. Electrolyte solution, according to claim 6, CHARACTERIZED by the fact that the tetraalkyl quaternary is triethylpropyl quaternary. 8. Electrolyte solution according to claim 5, CHARACTERIZED by the fact that the electrolyte solution additionally comprises one or more quaternary alkylpiperidinyl halides of the following structure: 9. Electrolyte solution, according to claim 8, CHARACTERIZED by the fact that X 'is Br' or Cl 'or a mixture thereof, and R1 and R ₂ are, independently, alkyl substituents that have 12 or less carbon atoms. 10. Electrolyte solution, according to claim 9, CHARACTERIZED by the fact that X 'is Br' and R1 and R ₂ , are, independently, ethyl, methyl or propyl. 11. Electrolyte solution, according to claim 9, CHARACTERIZED by the fact that R1 and R ₂ are both ethyl or are ethyl and propyl, respectively. Petition 870170010735, of 02/17/2017, p. 49/95 4/11 12. Electrolyte solution according to claim 1, CHARACTERIZED by the fact that the electrolyte solution additionally comprises one or more compounds that have a molecular structure selected from the group consisting of: R-, \ φ R _s -M-R4 / „Θ Rs * i Λ Ν © Χθ \ LOL II Petition 870170010735, of 02/17/2017, p. 50/95 5/11 IH IV SAW Petition 870170010735, of 02/17/2017, p. 51/95 6/11 in which X is Br or Cl or a mixture thereof, and R ₁ , R ₂ , R ₃ are, independently, hydrogen or alkyl substituents that have about 12 or less carbon atoms; R ₄ is an alkyl chain that has carbon atoms in the range of about 1 to about 10; and R ₆ , R ₇ and R ₈ are, independently, hydrogen or alkyl substituents that have 12 or less carbon atoms. 13. Electrolyte solution according to claim 1, CHARACTERIZED by the fact that R ₁ , R ₂ , R ₃ and R ₄ are, independently, ethyl or methyl. 14. Flow cell battery containing bromine CHARACTERIZED by the fact that it comprises an electrolyte as defined in any one of claims 1 to 13. 15. Zinc bromide flow cell battery, vanadium bromide flow cell battery, polysulfide bromine flow cell battery or hydrogen bromine flow cell battery CHARACTERIZED by the fact that comprising an electrolyte as defined in any one of claims 1 to 13. 16. Electrolyte solution, according to claim 12, CHARACTERIZED by the fact that R1, R2, R3 are independently hydrogen or alkyl substituents in the range of about 1 to about 7 carbon atoms. 17. Electrolyte solution according to claim 16, CHARACTERIZED by the fact that R1, R2, R3 are, independently, hydrogen or alkyl substituents in the range of about 1 or 2 to about 4 carbon atoms. 18. Electrolyte solution, according to claim 17, CHARACTERIZED by the fact that R4 is an alkyl chain that Petition 870170010735, of 02/17/2017, p. 52/95 7/11 in the range of 1 or 2 to 4 carbon atoms. 19. Electrolyte solution CHARACTERIZED by the fact that it comprises one or more class A quaternary halides, each of which has a molecular structure selected from the group consisting of: A- [tCH ^ E-O-fCHAfe-B where A and B are each independently selected from the group consisting of: Petition 870170010735, of 02/17/2017, p. 53/95 8/11 when E and F are each independently in the range of 1 to 10; n is in the range of 1 to 100; X 'is Br' or Cl ', or the quaternary is a mixture of both bromides and chlorides; Ri, R ₂ , R 3, are independently hydrogen or alkyl substituents that have about 12 or less carbon atoms; R ₄ is an alkyl chain that has carbon atoms in the range of about 1 to about 10; R ₅ is an alkyl group that has carbon atoms in the range of about 1 to about 6; and R ₆ , R7 and R ₈ are independently hydrogen or alkyl substituents that have 12 or less carbon atoms. 20. Electrolyte solution according to claim 19, CHARACTERIZED by the fact that R ^ R ₂ and R ₃ are, independently, hydrogen or alkyl substituents that have carbon atoms in the range of about 1 and about 7. 21. Electrolyte solution according to claim 19, CHARACTERIZED by the fact that R ₄ is an alkyl chain that has carbon atoms in the range of about 1 to about 4. 22. Electrolyte solution according to claim 19, CHARACTERIZED by the fact that R ₅ is an alkyl group that has carbon atoms in the range of about 1 to about 4. 23. Electrolyte solution, according to claim 19, CHARACTERIZED by the fact that the one or more class A quaternaries is (or are) twinned dimethylethyl quaternary bromide with diethylether bond which has the following structure: Petition 870170010735, of 02/17/2017, p. 54/95 9/11 C ₂ H ₅ - ch ₃ ch ₃ c ₂ h ₅ 24. Electrolyte solution, according to claim 19, CHARACTERIZED by the fact that it additionally comprises one or more class B quaternaries, each of which has the following structure: C- (CH ₂ ) nD where C and D are each independently selected from the group consisting of: on what X 'is Br- or Cl-, or the quaternary is a mixture of both bromides and chlorides; n is in the range of 1 to 100; R1, R ₂ , R3, are independently hydrogen or alkyl substituents that have about 12 or less carbon atoms; and Petition 870170010735, of 02/17/2017, p. 55/95 11/10 R ₆ , R7 and R ₈ are independently hydrogen or alkyl substituents that have 12 or less carbon atoms. 25. Electrolyte solution, according to claim 1, CHARACTERIZED by the fact that it additionally comprises one or more class B quaternaries, since each has the following structure: C- (CH2) n-D where C and D are each independently selected from the group consisting of: -NR ₂ | ^G V ^x θ F ?! on what X 'is Br- or Cl-, or the quaternary is a mixture of both bromides and chlorides; n is in the range of 1 to 100; R1, R ₂ , R3, are independently hydrogen or alkyl substituents that have about 12 or less carbon atoms; and R ₆ , R7 and R ₈ are independently hydrogen or alkyl substituents that have 12 or less carbon atoms. Petition 870170010735, of 02/17/2017, p. 56/95 11/11 26. Electrolyte solution according to claim 24, CHARACTERIZED by the fact that the one or more class B quaternaries is (or are) twinned dimethylethyl quaternary bromide with butyl bond which has the following structure: c ₂ h ₅ - Petition 870170010735, of 02/17/2017, p. 57/95 1/1